Medical radionuclide imaging, commonly referred to as nuclear medicine, is a significant diagnostic tool that involves the use of ionizing radiation to obtain accurate imaging of an in vivo patient. Typically, one or more biologically appropriate radiopharmaceuticals are administered to a patient, as by ingestion, inhalation, or injection. Tracer amounts of these radioactive substances emanate gamma quanta while localizing at specific organs, bones, or tissues of interest within the patient's body. One or more radiation detectors (e.g., positron emission tomography (PET) detector) are then used to record the internal spatial distribution of the radiopharmaceutical as it propagates from the study area. Known applications of nuclear medicine include: analysis of kidney function, imaging blood-flow and heart function, scanning lungs for respiratory performance, identification of gallbladder blockage, bone evaluation, determining the presence and/or spread of cancer, identification of bowel bleeding, evaluating brain activity, locating the presence of infection, and measuring thyroid function and activity. Hence, accurate detection is vital in such medical applications.
In position emission tomography (PET), certain detectors utilize a scintillator array and an array of photosensors to provide event localization within the scintillator array for 2-dimensional (2-D) imaging. However, it is readily apparent that 3-D information can be very advantageous, particularly in the above medical applications. With 3-D information, parallax errors can be reduced or eliminated within enough spatial resolution in the transaxial direction.
Traditionally, a monolithic scintillator can be used to obtain 3-D information. Unfortunately, this approach has the drawback of a reduced active area due to “edge effects.” That is, near edges (or corners) photons are not easily directed and can result in misinformation, thereby negatively impact imaging; notably the resolution is reduced. That is, when gamma interactions occur near the edges of monolithic scintillators, the light produced is not channeled or collected properly which can result in poor event localization. Monolithic blocks also suffer from poor event localization when the incoming gamma ray is at oblique angles to the front surface of the detector.
Based on the foregoing, there is a clear need for an improved detector for nuclear medicine imaging.